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Area Forecast Discussion (AFD)

Issued by Brownsville/Rio Grande Valley, TX (BRO)

FXUS64 KBRO 220521 AAA

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
1221 AM CDT Sun Sep 22 2019

.DISCUSSION...Updated for latest aviation discussion below.

.AVIATION...VFR will be the rule through the next 24 hours.
Moderate winds with breezy gusts are expected during the daylight
hours of Sunday. Isolated convection is anticipated, but will not
be widespread enough to warrant inclusion in the TAFs. 

.PREV DISCUSSION... /issued 625 PM CDT Sat Sep 21 2019/ 

DISCUSSION...Updated for latest aviation discussion below.

AVIATION...VFR conditions expected to prevail through the TAF
period, with isolated streamer showers across the east possible
tonight, mainly near BRO and east. Brief MVFR CIGs are possible 
near any showers, otherwise, expect partly cloudy skies. 
Confidence in shallow patchy fog is too low at this time to 
include, with better chances remaining north of the Rio Grande 

PREV DISCUSSION... /issued 302 PM CDT Sat Sep 21 2019/ 

SHORT TERM (Now through Sunday Night): 500 mb ridging will 
prevail over most of the Gulf Coast region throughout tomorrow 
while a deep 500 mb trough will dig into the western States. Good 
tropical moisture values will advect up ahead of the trough axis 
moving over the western and northern portions of the ridging from 
both the eastern Pac and the Gulf of Mex. This will likely 
maintain enough moisture and instability over the region to allow 
for some patchy mainly afternoon and early evening conv throughout
tomorrow evening. In addition, late night and early morning 
marine conv will also be possible. So will maintain some 20% pops 
mainly across the eastern areas through tomorrow night. 

Expect temps to remain near persistence throughout the short term
with the 500 mb ridging remain in place. The latest ECMWF temp 
guidance in the short term is the warmest compared to both the NAM
and GFS. Will lean towards the warmer side of the short term 
guidance as see no reason for temps to drop off much throughout 
Sun Night. 

After some coord with WFO CRP and taking a look at coastal web 
cams and the Brazos Santiago tidal data will go with a Coastal 
Flood Statement throughout tonight as observed tides are currently
running about 0.5 feet above predicted tide levels. Also 
predicted high tide by early Sunday morning will be just shy of 2 
ft above MLLW. 

LONG TERM (Monday through Saturday): An inverted trough will move 
west under the North Gulf Coast ridge on Monday, causing the ridge 
to retreat east slightly. At the same time, a mid level cutoff low 
will dig south down the West Coast, settling over the northern Baja 
Peninsula. The result will leave weakness aloft locally, and 
slightly enhanced chances for rain on at least Monday. The pattern 
will not change a whole lot during the week, with sufficient 
moisture available to keep isolated coastal/sea breeze convection in 
the forecast for the week. Late in the week, however, the cutoff low 
will eject northeast and mid level ridging will build west again 
toward the lower Texas Coast. Notwithstanding the return of the 
ridge aloft, moist southeast to south Gulf flow will persist at the 
surface, as will isolated to scattered rain probability. Maintained 
continuity with the inherited package, as overall trends did not 
change significantly. Just beyond the long term, another westward 
moving inverted trough will head into the Gulf and toward deep South 
Texas and the RGV early next week.

Temperatures will continue to trend warm and a few degrees above 
average, with the European model guidance coming in just a skosh 
drier and warmer than the GFS, as noted in the previous discussion. 
Heat index values will push up into the 103 to 108 degree range from 
mid week to Saturday.

Now through Sunday Night: The broad and persistent surface 
ridging will maintain a moderate SE low level flow throughout 
tomorrow evening. This will keep the Bay and Gulf conditions in 
SCEC territory throughout the short term period. Buoy020 and the 
Bay METARs have been persistently in the 15 to 20 knot range today
with Buoy020 reporting swells near 5 ft. 

Monday through Thursday Night: Generally light to moderate 
southeast winds and moderate seas will continue through the long 
term, with broad high pressure over the Gulf. Offshore seas will 
remain slightly higher transitioning into the long term, from 
Monday into Tuesday, and small craft should exercise caution to 
brief low end small craft advisory conditions will be possible 
early in the period. Isolated to scattered showers and tstorms 
will remain possible as conditions remain unsettled over the Gulf 
for most of the period.



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